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123 lines
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<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function SUBSTITUTE, SUBSTITUTE-IF...</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="f_replac.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_sequen.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_concat.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="substitute"><A NAME="substitute-if"><A NAME="substitute-if-not"><A NAME="nsubstitute"><A NAME="nsubstitute-if"><A NAME="nsubstitute-if-not"><I>Function</I> <B>SUBSTITUTE, SUBSTITUTE-IF, SUBSTITUTE-IF-NOT, NSUBSTITUTE, NSUBSTITUTE-IF, NSUBSTITUTE-IF-NOT</B></A></A></A></A></A></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>substitute</B> <I>newitem olditem sequence <TT>&key</TT> from-end test test-not start end count key</I><P> => <I>result-sequence</I><P>
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<P>
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<B>substitute-if</B> <I>newitem predicate sequence <TT>&key</TT> from-end start end count key</I><P> => <I>result-sequence</I><P>
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<P>
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<B>substitute-if-not</B> <I>newitem predicate sequence <TT>&key</TT> from-end start end count key</I><P> => <I>result-sequence</I><P>
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<P>
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<B>nsubstitute</B> <I>newitem olditem sequence <TT>&key</TT> from-end test test-not start end count key</I><P> => <I>sequence</I><P>
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<P>
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<B>nsubstitute-if</B> <I>newitem predicate sequence <TT>&key</TT> from-end start end count key</I><P> => <I>sequence</I><P>
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<P>
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<B>nsubstitute-if-not</B> <I>newitem predicate sequence <TT>&key</TT> from-end start end count key</I><P> => <I>sequence</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>newitem</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <P>
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<I>olditem</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <P>
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<I>sequence</I>---a <A REL=DEFINITION HREF="26_glo_p.htm#proper_sequence"><I>proper sequence</I></A>. <P>
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<I>predicate</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of one <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>argument</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>from-end</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. The default is <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A>. <P>
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<I>test</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>test-not</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>start</I>, <I>end</I>---<A REL=DEFINITION HREF="26_glo_b.htm#bounding_index_designator"><I>bounding index designators</I></A> of <I>sequence</I>. The defaults for <I>start</I> and <I>end</I> are <TT>0</TT> and <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, respectively. <P>
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<I>count</I>---an <A REL=DEFINITION HREF="26_glo_i.htm#integer"><I>integer</I></A> or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. The default is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>key</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of one argument, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>result-sequence</I>---a <A REL=DEFINITION HREF="26_glo_s.htm#sequence"><I>sequence</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#substitute"><B>substitute</B></A>, <A REL=DEFINITION HREF="#substitute-if"><B>substitute-if</B></A>, and <A REL=DEFINITION HREF="#substitute-if-not"><B>substitute-if-not</B></A> return a copy of <I>sequence</I> in which each <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>element</I></A> that <I>satisfies the test</I> has been replaced with <I>newitem</I>. <P>
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<A REL=DEFINITION HREF="#nsubstitute"><B>nsubstitute</B></A>, <A REL=DEFINITION HREF="#nsubstitute-if"><B>nsubstitute-if</B></A>, and <A REL=DEFINITION HREF="#nsubstitute-if-not"><B>nsubstitute-if-not</B></A> are like <A REL=DEFINITION HREF="#substitute"><B>substitute</B></A>, <A REL=DEFINITION HREF="#substitute-if"><B>substitute-if</B></A>, and <A REL=DEFINITION HREF="#substitute-if-not"><B>substitute-if-not</B></A> respectively, but they may modify <I>sequence</I>. <P>
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If <I>sequence</I> is a <A REL=DEFINITION HREF="26_glo_v.htm#vector"><I>vector</I></A>, the result is a <A REL=DEFINITION HREF="26_glo_v.htm#vector"><I>vector</I></A> that has the same <A REL=DEFINITION HREF="26_glo_a.htm#actual_array_element_type"><I>actual array element type</I></A> as <I>sequence</I>. If <I>sequence</I> is a <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A>, the result is a <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A>. <P>
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<I>Count</I>, if supplied, limits the number of elements altered; if more than <I>count</I> <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>elements</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#satisfy_the_test"><I>satisfy the test</I></A>, then of these <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>elements</I></A> only the leftmost or rightmost, depending on <I>from-end</I>, are replaced, as many as specified by <I>count</I>. If <I>count</I> is supplied and negative, the behavior is as if zero had been supplied instead. If <I>count</I> is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, all matching items are affected. <P>
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Supplying a <I>from-end</I> of <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> matters only when the <I>count</I> is provided (and <A REL=DEFINITION HREF="26_glo_n.htm#non-nil"><I>non-nil</I></A>); in that case, only the rightmost <I>count</I> <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>elements</I></A> <I>satisfying the test</I> are removed (instead of the leftmost). <P>
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<I>predicate</I>, <I>test</I>, and <I>test-not</I> might be called more than once for each <A REL=DEFINITION HREF="26_glo_s.htm#sequence"><I>sequence</I></A> <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>element</I></A>, and their side effects can happen in any order. <P>
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The result of all these functions is a <A REL=DEFINITION HREF="26_glo_s.htm#sequence"><I>sequence</I></A> of the same <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> as <I>sequence</I> that has the same elements except that those in the subsequence <A REL=DEFINITION HREF="26_glo_b.htm#bounded"><I>bounded</I></A> by <I>start</I> and <I>end</I> and <I>satisfying the test</I> have been replaced by <I>newitem</I>. <P>
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<A REL=DEFINITION HREF="#substitute"><B>substitute</B></A>, <A REL=DEFINITION HREF="#substitute-if"><B>substitute-if</B></A>, and <A REL=DEFINITION HREF="#substitute-if-not"><B>substitute-if-not</B></A> return a <I>sequence</I> which can share with <I>sequence</I> or may be <A REL=DEFINITION HREF="26_glo_i.htm#identical"><I>identical</I></A> to the input <I>sequence</I> if no elements need to be changed. <P>
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<A REL=DEFINITION HREF="#nsubstitute"><B>nsubstitute</B></A> and <A REL=DEFINITION HREF="#nsubstitute-if"><B>nsubstitute-if</B></A> are required to <A REL=DEFINITION HREF="m_setf_.htm#setf"><B>setf</B></A> any <A REL=DEFINITION HREF="f_car_c.htm#car"><B>car</B></A> (if <I>sequence</I> is a <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A>) or <A REL=DEFINITION HREF="f_aref.htm#aref"><B>aref</B></A> (if <I>sequence</I> is a <A REL=DEFINITION HREF="26_glo_v.htm#vector"><I>vector</I></A>) of <I>sequence</I> that is required to be replaced with <I>newitem</I>. If <I>sequence</I> is a <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A>, none of the <A REL=DEFINITION HREF="26_glo_c.htm#cdr"><I>cdrs</I></A> of the top-level <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A> can be modified. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(substitute #\. #\SPACE "0 2 4 6") => "0.2.4.6"
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(substitute 9 4 '(1 2 4 1 3 4 5)) => (1 2 9 1 3 9 5)
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(substitute 9 4 '(1 2 4 1 3 4 5) :count 1) => (1 2 9 1 3 4 5)
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(substitute 9 4 '(1 2 4 1 3 4 5) :count 1 :from-end t)
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=> (1 2 4 1 3 9 5)
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(substitute 9 3 '(1 2 4 1 3 4 5) :test #'>) => (9 9 4 9 3 4 5)
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(substitute-if 0 #'evenp '((1) (2) (3) (4)) :start 2 :key #'car)
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=> ((1) (2) (3) 0)
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(substitute-if 9 #'oddp '(1 2 4 1 3 4 5)) => (9 2 4 9 9 4 9)
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(substitute-if 9 #'evenp '(1 2 4 1 3 4 5) :count 1 :from-end t)
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=> (1 2 4 1 3 9 5)
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(setq some-things (list 'a 'car 'b 'cdr 'c)) => (A CAR B CDR C)
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(nsubstitute-if "function was here" #'fboundp some-things
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:count 1 :from-end t) => (A CAR B "function was here" C)
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some-things => (A CAR B "function was here" C)
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(setq alpha-tester (copy-seq "ab ")) => "ab "
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(nsubstitute-if-not #\z #'alpha-char-p alpha-tester) => "abz"
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alpha-tester => "abz"
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B><P>
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<P>
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<A REL=DEFINITION HREF="#nsubstitute"><B>nsubstitute</B></A>, <A REL=DEFINITION HREF="#nsubstitute-if"><B>nsubstitute-if</B></A>, and <A REL=DEFINITION HREF="#nsubstitute-if-not"><B>nsubstitute-if-not</B></A> modify <I>sequence</I>. <P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B><P>
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<P>
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Should be prepared to signal an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_tp_err.htm#type-error"><B>type-error</B></A> if <I>sequence</I> is not a <A REL=DEFINITION HREF="26_glo_p.htm#proper_sequence"><I>proper sequence</I></A>. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="f_substc.htm#subst"><B>subst</B></A>, <A REL=DEFINITION HREF="f_substc.htm#nsubst"><B>nsubst</B></A>, <A REL=CHILD HREF="03_ba.htm">Section 3.2.1 (Compiler Terminology)</A>, <A REL=CHILD HREF="03_f.htm">Section 3.6 (Traversal Rules and Side Effects)</A> <P>
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<P><B>Notes:</B><P>
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<P>
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If <I>sequence</I> is a <A REL=DEFINITION HREF="26_glo_v.htm#vector"><I>vector</I></A>, the result might or might not be simple, and might or might not be <A REL=DEFINITION HREF="26_glo_i.htm#identical"><I>identical</I></A> to <I>sequence</I>. <P>
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The <TT>:test-not</TT> <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>argument</I></A> is deprecated. <P>
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The functions <A REL=DEFINITION HREF="#substitute-if-not"><B>substitute-if-not</B></A> and <A REL=DEFINITION HREF="#nsubstitute-if-not"><B>nsubstitute-if-not</B></A> are deprecated. <P>
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<A REL=DEFINITION HREF="#nsubstitute"><B>nsubstitute</B></A> and <A REL=DEFINITION HREF="#nsubstitute-if"><B>nsubstitute-if</B></A> can be used in for-effect-only positions in code. <P>
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Because the side-effecting variants (e.g., <A REL=DEFINITION HREF="#nsubstitute"><B>nsubstitute</B></A>) potentially change the path that is being traversed, their effects in the presence of shared or circular structure may vary in surprising ways when compared to their non-side-effecting alternatives. To see this, consider the following side-effect behavior, which might be exhibited by some implementations: <P>
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<PRE>
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(defun test-it (fn)
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(let ((x (cons 'b nil)))
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(rplacd x x)
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(funcall fn 'a 'b x :count 1)))
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(test-it #'substitute) => (A . #1=(B . #1#))
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(test-it #'nsubstitute) => (A . #1#)
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</PRE>
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</TT> <P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss345.htm">TEST-NOT-IF-NOT:FLUSH-ALL</A><LI> <A REL=CHILD HREF="../Issues/iss240.htm">MAPPING-DESTRUCTIVE-INTERACTION:EXPLICITLY-VAGUE</A><LI> <A REL=CHILD HREF="../Issues/iss083.htm">CONSTANT-MODIFICATION:DISALLOW</A><LI> <A REL=CHILD HREF="../Issues/iss293.htm">REMF-DESTRUCTION-UNSPECIFIED:X3J13-MAR-89</A><LI> <A REL=CHILD HREF="../Issues/iss283.htm">RANGE-OF-COUNT-KEYWORD:NIL-OR-INTEGER</A><LI> <A REL=CHILD HREF="../Issues/iss284.htm">RANGE-OF-START-AND-END-PARAMETERS:INTEGER-AND-INTEGER-NIL</A><LI> <A REL=CHILD HREF="../Issues/iss332.htm">SUBSEQ-OUT-OF-BOUNDS</A><P></UL><HR>
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<A REL=COPYRIGHT HREF="../Front/Help.htm#Legal"><I>Copyright 1996-2005, LispWorks Ltd. All rights reserved.</I></A><P>
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